JPH09232702A - Structure of printed-wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the direction of pads and the directions of components constant to the flow of solder in a solder tank and to stabilize the feeding of the solder to the terminals of a surface mount component by a method wherein an insertion direction display part is formed on the printed-wiring board to show the direction of a printed-wiring board in the solder tank. SOLUTION: Electronic components, such as a large-scale integrated circuit 1, a diode 2, a capacitor 3 and a component 4, are mounted on the surface part of a printed-wiring board 11 and terminals of the circuit 1 and terminals of the diode 2 and the component 4 are connected with each other according to their functions like patterns 5 as one example. An insertion direction display part 10 to show the direction of the board 11 into a solder tank is provided on one side of the surface 11-1 of the board 11. Thereby, in the case where the board 11 is inserted in the solder tank, the board 11 is never inserted in the tank from directions other than the direction, which is shown by the display part 10. As a result, the direction of pads 8 and the directions of the components are kept constant to the flow of solder in the tank, the feeding of the solder is stabilized to the terminals of the surface mount component 1 and the structure of a highly reliable printed-wiring board can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board structure mounted on communication equipment.

[0002]

2. Description of the Related Art A printed wiring board is provided with a copper clad laminate on an insulating material and has a pad for mounting and connecting electronic parts or an electronic part mounting hole, and each connection is made by a copper pattern. After mounting the electronic parts, the electronic parts were fixed by soldering. 2. Description of the Related Art In recent years, surface mounting is becoming the mainstream of electronic component mounting as the size and weight of devices are becoming smaller and lighter.
Among the mounted electronic components of the printed wiring board, there is a method of providing an electronic component mounting hole in the printed wiring board, inserting a lead terminal of the electronic component (discrete component) into the electronic component mounting hole, and mounting by soldering.

Usually, both surface mounting of electronic components and fixing using electronic component mounting holes are generally mixedly mounted on a printed wiring board. In this case, soldering is performed by mounting electronic components on a printed wiring board in a solder bath in which the solder is melted, immersing the printed wiring board, and then fixing it with solder.

[0004]

An electronic component mounting hole is provided in a printed wiring board, an electronic component terminal is inserted into the electronic component mounting hole, and surface mounting is performed on a surface mounting pad provided on the printed wiring board. After mounting the electronic parts, the electronic parts are fixed through a soldering process in which the printed wiring board is immersed in a solder bath in order to fix each electronic part.
At this time, the surface mount component has a problem in that the solder is not sufficiently attached depending on the component direction and the pad direction or the shape depending on the insertion direction into the solder bath and the connection with the component is insufficient, resulting in lack of reliability.

In general, many printed wiring boards have a quadrangular shape, and in order to improve solderability, the component direction and the pad direction or the shape are aligned in one direction.
In some cases, when entering the soldering process, it was not clear from which direction the soldering bath should be placed.

The present invention has been made in view of the above problems, and its object is to keep the pad direction and the component direction always constant with respect to the flow of solder in the solder bath, It is an object of the present invention to provide a printed wiring board structure in which solder is stably supplied to terminals of mounted components and which has high reliability.

[0007]

To achieve the above object, a printed wiring board structure according to the first aspect of the present invention comprises:
In a printed wiring board structure in which electronic components are mounted on a printed wiring board and the components are fixed by soldering to form an electric circuit, an insertion direction display portion indicating a solder bath insertion direction is displayed on the printed wiring board. Characterize.

With this configuration, when the printed wiring board is put in the solder bath, the printed wiring board is not put in from a direction other than the direction indicated by the insertion direction display portion. Therefore, the pad direction and the component direction are always constant with respect to the flow of solder in the solder bath, and it is possible to provide a highly reliable printed wiring board structure in which the solder is stably supplied to the terminals of the surface mount component. .

Further, in order to achieve the above object, the printed wiring board structure according to the invention of claim 2 is the printed wiring board structure according to claim 1, wherein the insertion direction display portion is provided on the printed wiring board. It was formed in the silk printing process of the manufacturing process.

With this structure, not only the same operation as the operation of the first aspect of the present invention described above can be achieved, but also the display section can be formed by the silk printing process at the time of manufacturing the printed wiring board.

In order to achieve the above-mentioned object, a printed wiring board structure according to the invention of claim 3 is the printed wiring board structure according to claim 1, wherein the insertion direction display portion is provided on the printed wiring board. It was formed in the etching process of the manufacturing process.

With this structure, not only the same operation as the operation of the first aspect of the invention described above can be achieved, but also the insertion direction display portion can be formed in the etching step at the time of manufacturing the printed wiring board.

Further, in order to achieve the above object, the printed wiring board structure according to the invention of claim 4 is the printed wiring board structure according to claim 1, claim 2 or claim 3, The portion was formed so as to be perpendicular to the pad of the surface mount component mounted on the printed wiring board.

With such a construction, not only the same operation as that of the invention of claim 1 described above can be achieved, but also since the pads are arranged at a right angle to the insertion direction of the solder bath, the solder flow can be dealt with and the solder flow Good attachment.

Further, in order to achieve the above object, the printed wiring board structure according to the invention of claim 5 is the printed wiring board structure according to claim 4, wherein in the longitudinal direction of the pad of the surface mount component, The solder area was increased by forming a protrusion longer than the component terminal of the surface mount component.

With such a construction, not only the same operation as the operation of the invention of claim 4 described above can be achieved, but also since the solder is enlarged by providing the protrusion in the longitudinal direction of the pad to increase the solder area. When it adheres to the protrusions, the surface tension causes the solder to be attracted toward the pad to be soldered.

For this reason, in a surface mount component having three component terminals, the solder is sufficiently attached to one component terminal close to the solder flow in the solder flow direction. Other component terminals in the direction are difficult to solder by being interfered by one component terminal, but as described above, since the protrusion is provided in the longitudinal direction of the pad to increase the solder area, Supports solder flow and has good solderability.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view of a front surface side of a printed wiring board structure according to the present invention, FIG. 2 is a perspective view of a back surface side of the same printed wiring board structure, and FIG. 3 is a side view of the same printed wiring board structure.

Electronic components such as a large scale integrated circuit (LSI) 1, a diode 2, a capacitor 3 and a component 4 are mounted on the surface of the printed wiring board 11, and the terminals are patterned according to their functions as an example. 5 are connected. This pattern 5 is usually made of copper. And
On one side of the surface 11-1 of the printed wiring board 11, there is provided an insertion direction display portion 10 showing the insertion direction into the solder bath.

The surface 11-1 of the printed wiring board 11
Includes discrete components (electronic components with lead terminals)
The lead terminal T-1 (3
-1, 4-1) are provided with lead mounting holes 7 for inserting and mounting, respectively, and have lands 6 as portions to which solder is attached. The land 6 is made of copper so that the solder can be placed thereon.

Further, the large-scale integrated circuit (LSI) 1 and the diode 2 which are the surface mount components S are the printed wiring board 11
Since it is mounted on the surface 11-1 of the printed wiring board 11,
As shown in FIG. 4, a pad 8 corresponding to the terminal shape of the surface-mounted component S to be mounted thereon is formed by the copper exposed portion, and as shown in FIG. 5, the pad 8 and the component terminals 1-1, 2-1 are formed. And solder 9
Connected by

The insertion direction display portion 10 showing the insertion direction of the solder bath is formed during the manufacturing process of the printed wiring board 11 shown in FIG. The manufacturing process of the printed wiring board 11 shown in FIG. 8 includes a printed wiring board manufacturing process A and an assembly process B.

In the printed wiring board manufacturing step A, first, a step of preparing a copper clad laminate in which a copper foil is adhered and adhered to an ordinary insulating material is prepared (step S1), and lead mounting holes are formed in the copper clad laminate. 7 and a via hole for passing a portion of the printed wiring board 11 where the pattern does not pass through the front surface 11-1 and the back surface 11-2 from the front surface 11-1 to the back surface 11-2 or from the back surface 11-2 to the front surface 11-1 (see FIG. (Not shown) and a step of performing NC drilling such as fixed mounting holes (not shown) of the printed wiring board 11 (step S2), and the printed wiring board 11 includes lands 6 and pads 8 for mounting electronic components. Alternatively, since copper other than the pattern 5 is unnecessary, a pattern printing step (step S3) of performing pattern printing to leave a necessary portion and an etching step (step of removing extra copper other than the pattern 5 etc. S4), a resist printing step (step S5) for preventing solder from being attached unless necessary in the soldering step, and a silk (silk screen) printing for displaying the insertion direction display portion 10, the component mounting step, and the necessary product name. The process (step S6) and the outer shape of the printed wiring board 11 are N
External processing process (Step S
7), a check step for confirming the appearance and the connection state of the pattern (step S8), and the surface of the exposed copper such as the land 6 and the pad 8 is subjected to anticorrosion treatment so as not to deteriorate solderability such as oxidation. And a surface treatment step (step S9).

In the assembly process B, a necessary component is mounted on the printed wiring board 11 by an automatic machine (or a component which cannot be mounted by the automatic machine is manually mounted), a component automatic mounting process (step S10, step). S11), a soldering step (step S12) of inserting into a solder bath to fix these components and soldering, and an inspection step (step S1).
3) and a main body incorporating step (step S14).

Then, in the silk (silk screen) printing process of step S6, the insertion direction display portion 10 is displayed together with the component mounting process and the display of the necessary product name.

The printed wiring board 11 has a front surface 11-1.
And both sides of the back surface 11-2. For example, it is best that the components can be mounted only on the front surface 11-1, but in order to achieve high density and high mounting, both the front surface 11-1 and the back surface 11-2 are mounted as shown in FIG. Electronic components T, S, S-1 and S-2 are mounted on.

As shown in FIG. 6, one surface mount component S
-1 is mounted on a pad 8 provided on the back surface 11-2 of the printed wiring board 11. The surface mount component S-1 is a component terminal 1
Although it has two terminals as 2, the two pads 8 are arranged at right angles to the solder bath insertion direction (a), so that it is possible to cope with the flow of solder in the solder flow direction C indicated by the arrow and the solderability is improved. Is good.

However, the other surface mount component S-2 has three terminals as the component terminals 13-1, 13-2, 13-3, and in the solder flow direction C, the component terminal 13-1,
Since 13-2 are arranged at right angles, the solder is sufficiently attached to the component terminal 13-1 near the flow of solder, but the component terminal 13-2 in the rear direction of the component terminal 13-1 is The terminal 13-1 interferes with the solderability.

Therefore, the surface area of the solder is utilized to provide the protrusion 14 in the longitudinal direction of the pad 8 to increase the solder area. The protrusion 14 is formed by the component terminals 13-1, 13-
It is longer than 2, 13-3. When the solder adheres to these protrusions 14, the solder is attracted toward the pad 8 by the surface tension and soldered.

This double-sided soldering process is performed in the printed wiring board 1
The surface mount components S-1 and S-2 which are surface-mounted on the back surface 11-2 of 1 are fixed to a predetermined position where each of the printed wiring boards 11 is mounted with an adhesive. After that, the surface mount component S to be mounted on the surface 11-1 is mounted. The surface mount component S applies cream solder to the pad 8 and melts and fixes the cream solder by heat. Then, with the front surface 11-1 facing up and the back surface 11-2 facing down, the front surface 11-1
The insertion direction display portion 10 shown in (1) is placed in the solder bath and the back surface 11-2 side is fixed by the solder 9.

Since the surface-mounted component S on the back surface 11-2 side is already fixed on the printed wiring board 11 with an adhesive, it does not fall even if the back surface 11-2 is turned down. Further, since there is the discrete component T on the front surface 11-1 side, this lead terminal T-1 is exposed on the back surface 11-2 side. Therefore, when the printed wiring board 11 is placed in the solder tank with the back surface 11-2 side down, the solder is attached to the lead terminals T-1 on the back surface 11-2 side and the solder is also attached to the land 6. Land 6 and lead terminal T-1 are fixed.

According to the above-described embodiment, the insertion direction display portion 1 showing the solder bath insertion direction B on the printed wiring board 11 is shown.
Since there is 0, when the printed wiring board 11 is put into the solder bath, the printed wiring board 11 cannot be put in from a direction other than the direction shown by the solder bath insertion display portion 10. For this,
The direction of the pad 8 and the direction of the electronic component are always constant with respect to the flow of the solder 9 in the solder bath, and the surface mount components S, S-1, S
-2 component terminals 1-1, 1-2, 12, 13-1, 13
It is possible to provide the printed wiring board 11 having a stable supply of the solder 9 and the highly reliable printed wiring board 11.

Further, the insertion direction display portion 10 is formed of silk or copper foil so as to be perpendicular to the pads 8 of the surface mount components S, S-1, S-2 mounted on the printed wiring board 11. be able to.

Further, in the above-described embodiment, the insertion direction display portion 10 indicating the solder bath insertion direction C is formed in the silk (silk screen) printing process, but the insertion direction is left while etching copper in the etching process. The display unit 10 may be formed. In this case, it is necessary to apply a resist on the copper.

[0035]

As described above, according to the printed wiring board structure of the first aspect of the present invention, the electronic component is mounted on the printed wiring substrate and the component is fixed by soldering to form an electric circuit. In the wiring board structure, by forming the insertion direction display portion showing the solder bath insertion direction on the printed wiring board, when the printed wiring board is put in the solder bath, the direction other than the direction shown by the insertion direction display portion of the printed wiring board is used. You can't enter from the direction. Therefore, the pad direction and the component direction are always constant with respect to the flow of solder in the solder bath, and it is possible to provide a highly reliable printed wiring board structure in which the solder is stably supplied to the terminals of the surface mount component.

According to the printed wiring board structure of the second aspect of the present invention, in the printed wiring board structure of the first aspect, the insertion direction display portion is formed by a silk printing process in a manufacturing process of the printed wiring board. By forming it, not only the same effect as the effect of the invention of claim 1 described above can be obtained, but also the insertion direction display portion can be formed by the silk printing process at the time of manufacturing the printed wiring board.

According to the printed wiring board structure of the third aspect of the present invention, in the printed wiring board structure of the first aspect, the insertion direction display portion is formed in the etching step of the manufacturing process of the printed wiring board. By doing so, not only the same effects as the effects of the invention of claim 1 described above can be obtained, but also the insertion direction display portion can be formed in the etching step at the time of manufacturing the printed wiring board.

According to the printed wiring board structure according to the invention of claim 4, claim 1 or claim 2 or claim 3
The printed wiring board structure according to claim 1, wherein the insertion direction display portion is formed so as to be perpendicular to a pad of a surface mount component mounted on the printed wiring board. Not only can the same effects as the effects be obtained, but since the pads are arranged at right angles to the solder bath insertion direction, it is possible to cope with the flow of solder and the solderability is good.

According to the printed wiring board structure of the fifth aspect of the present invention, in the printed wiring board structure of the fourth aspect, the component terminals of the surface mount component are arranged in the longitudinal direction of the pads of the surface mount component. The method according to claim 4, wherein the longer protrusion is formed to increase the solder area.
Not only can the same effects as those of the invention of the present invention be exhibited, but since the solder area is enlarged by providing the protrusions in the longitudinal direction of the pad, when the solder adheres to these protrusions, the surface tension causes the solder. It is pulled toward the pad and soldered.

For this reason, in the surface mount component having three component terminals, the solder is sufficiently attached to one component terminal close to the solder flow in the solder flow direction. Other component terminals in the direction are difficult to solder by being interfered by one component terminal, but as described above, since the protrusion is provided in the longitudinal direction of the pad to increase the solder area, Supports solder flow and has good solderability.

[Brief description of drawings]

FIG. 1 is a perspective view of a front surface side of a printed wiring board structure according to the present invention.

FIG. 2 is a perspective view of a back surface side of the same printed wiring board structure.

FIG. 3 is a side view of the same printed wiring board structure.

FIG. 4 is an explanatory diagram of a pad shape of a surface mount component of the same printed wiring board structure.

FIG. 5 is a side view of a mounted state of surface mount components in the same printed wiring board structure.

FIG. 6 is an explanatory diagram of a solder flow direction and a pad of one surface mount component.

FIG. 7 is an explanatory diagram of a solder flow direction and a pad of another surface mount component.

FIG. 8 is a flowchart of a manufacturing process of a printed wiring board.

[Explanation of symbols]

1 Large Scale Integrated Circuit (LSI) (Surface Mounted Components, Electronic Components) 2 Diodes (Surface Mounted Components, Electronic Components) 3 Capacitors (Discrete Components) 6 Lands 8 Pads 9 Solders 10 Insertion Direction Indicators 11 Printed Wiring Boards

Claims (5)

[Claims] 1. An electronic component is mounted on a printed wiring board,
In a printed wiring board structure in which an electronic component is fixed by soldering to form an electric circuit, an insertion direction display portion showing a solder bath insertion direction is formed on the printed wiring board. 2. The printed wiring board structure according to claim 1, wherein the insertion direction display portion is formed by a silk printing process in a manufacturing process of the printed wiring board. 3. The printed wiring board structure according to claim 1, wherein the insertion direction display portion is formed in an etching step of a manufacturing process of the printed wiring board. 4. The print according to claim 1, wherein the insertion direction display section is formed so as to be perpendicular to a pad of a surface mount component mounted on the printed wiring board. Wiring board structure. 5. The printed wiring board structure according to claim 4, wherein a protrusion area is formed in a longitudinal direction of the pad of the surface mount component to increase a solder area.